Aircraft engine run-up hangar

ABSTRACT

An aircraft engine run-up hangar comprises a building defining a test chamber capable of receiving an aircraft therein, an air inlet structure, and an exhaust structure. The air inlet structure is formed in a front end part of a roof structure corresponding to a front end part of the building. The exhaust structure is connected to a rear end part of the building and defines an exhaust passage extending obliquely upward from the back end of the building. A ceiling included in the building has an inclined section sloping down backward to straighten air currents, and a groove is formed in a middle part, with respect to width, of the inclined section to permit a vertical tail fin of an aircraft to pass when the aircraft is carried into or out of the test chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an aircraft engine run-up hangar and, more specifically, to an aircraft engine run-up hangar incorporating improvements in the disposition of an air inlet structure, the construction of the ceiling of a test chamber, and construction of an exhaust structure through which gases are discharged from the test chamber, and capable of producing stable air currents in the test chamber.

2. Description of the Related Art

An overhauled aircraft engine or an aircraft engine of an aircraft to be placed in commission is subjected to a ground run-up in an open space for performance test. Various noise control measures have been taken for environmental protection. Generally, a noise-suppressing duct is disposed just behind the exhaust cone of the engine for, outdoor run-up. Some recent run-up method uses a building capable of entirely housing an aircraft therein and having a noise control function, which is called a noise control hangar. Generally, an air inlet structure included in a noise control hangar is incorporated into the front end part of the noise control hangar to take air into the noise control hangar. Such a noise control hangar of a front air inlet type is provided with a big door provided with an air inlet structure having current-straightening and noise control functions at its front end. This big door must be opened when carrying an aircraft into or out of the noise control hangar. The air inlet structure having current-straightening and noise control functions is inevitably long and, consequently, the big door provided with the long air inlet structure is inevitably very thick. The thickness of a big door included in a practical noise control hangar of a front inlet type is as big as 7.5 m.

Operations for opening and closing the big door provided with the air inlet structure and having a big thickness to carry an aircraft into or out of the noise control hangar need a large-scale door operating mechanism, and a large operating space is necessary for moving and storing the big door provided with the air inlet structure. Thus, the thick big door and the large operating space increase equipment costs. Moreover, the air inlet structure provides a large intake resistance and hence the back flow of exhaust gas is liable to occur in the noise control hangar. If wind blows outside across a direction in which air flows into the air inlet, it is difficult to produce uniform air currents by straightening air taken in through the air inlet and hence it is difficult to carry out the run-up of the aircraft engine under proper run-up conditions.

A previously proposed noise control hangar is provided with an air inlet in a front end part of the roof structure of the noise control hangar instead of in the front end of the noise control hangar. A noise control hangar proposed in, for example, JP-A 318696/2000 is provided with an air inlet formed in a front end part of the roof structure of the noise control hangar corresponding to the front end part of the noise control hangar, and an exhaust duct to be connected to the exhaust port of an aircraft engine and placed in the test chamber defined by the noise control hangar. Exhaust gas discharged from the aircraft engine is discharged outside through an exhaust line arranged in a back end part of the noise control hangar during the run-up of the aircraft engine. The exhaust duct must be moved every time aircrafts are changed and much labor is necessary for moving the exhaust duct. A noise control hangar disclosed in JP-A 313399/2000 has a roof structure provided with an inlet opening in a front end part thereof corresponding to the front end part of the noise control hangar, and is provided with an exhaust line extending backward and upward from the back end of a test chamber, and circulation-preventive plates having a J-shaped cross section disposed on a part of a ceiling in a back part of the test chamber to prevent the circulation of the exhaust gas.

In the prior art noise control hangar disclosed in JP-A 313399/2000, the ceiling of the noise control hangar is at a level above that of the tip of the vertical tail fin of the aircraft to enable the high vertical tail fin move under the ceiling. Therefore, the noise control hangar inevitably has a useless space in an upper region of the test chamber. Since the noise control hangar is not provided with any current straightening plates or the like for straightening air currents flowing in the useless space, the exhaust gas discharged from the engine tends to flow forward through the useless space in the test chamber, and air currents are liable to produce eddies and turbulent flows. Consequently, the exhaust gas is liable to be sucked into the engine of the aircraft and hence it difficult to carry out the run-up of the engine of the aircraft under proper conditions.

Although the circulation-preventive plates are disposed slightly in front of the tail fins of the aircraft, the exhaust gas tends to flow forward and whirling currents are liable to be produced in a region in front of the circulation-preventive plates because the large useless space extends on the front side of the circulation-preventive plates.

Since the exhaust gas produced in this noise control hangar is discharged from the back end of the test chamber directly into the exhaust line, the exhaust gas currents is accompanied by a large amount of accompanying currents, i.e., an amount as large as about four times the amount of the exhaust gas currents, during the run-up of the engine. However, any accompanying currents capable of preventing the reverse flow of the exhaust gas cannot be produced because the nose control hangar is not provided with any current straightening means for making the accompanying currents flow regularly backward.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an aircraft engine run-up hangar including a building defining a test chamber and having a roof structure provided with an air inlet, capable of deflecting air currents flowing through the air inlet into the building toward an aircraft housed in the building, to provide an aircraft engine run-up hangar capable of making an exhaust gas flow from a test chamber directly into an exhaust passage, and to provide an aircraft engine run-up hangar capable of producing accompanying currents capable of preventing the reverse flow of an exhaust gas in a test chamber.

According to the present invention, an aircraft engine run-up hangar includes: a building defining a test chamber capable of receiving an aircraft therein; an air inlet structure; and an exhaust structure; wherein the air inlet structure is formed in a front end part of a roof structure corresponding to a front end part of the building, the exhaust structure is connected to a rear end part of the building and defines an exhaust passage extending obliquely upward from the back end of the building, a ceiling included in the building has an inclined section sloping down backward to straighten air currents, and, a groove is formed in a middle part, with respect to the width, of the inclined section to permit the vertical tail fin of an aircraft to pass when the aircraft is carried into or out of the test chamber.

The air inlet structure is disposed on the roof structure and hence a large door for closing a large opening through which the aircraft is carried into or out of the building does not need to be provided with any air inlet structure, and the large door may be of simple construction similar to that of an ordinary soundproof door. Therefore any space for moving and storing the large door is not necessary, which is favorable to saving space necessary for installing the aircraft engine run-up hangar and is convenient in incorporating various current-straightening means into the air inlet structure. Since the exhaust structure is connected to the rear end part of the building so as to form the exhaust passage extending obliquely upward from the back end of the building, any work for moving an exhaust duct is not necessary when aircrafts are changed. Since air in the test chamber is discharged upward through the back end part of the building, the exhaust structure has a comparatively short length and needs a comparatively small space for installation behind the building, which is favorable to saving space necessary for installing the aircraft engine run-up hangar.

Since the ceiling has the inclined section sloping down backward and the groove is formed in a middle part, with respect to the width, of the inclined section to permit the vertical tail fin of an aircraft to pass when the aircraft is carried into or out of the test chamber, the inclined section can be extended in a region far below the tip of the vertical tail fin, the inclined section sloping down backward controls the accompanying currents accompanying the current of the exhaust gas so as to flow regularly backward to produce the accompanying currents capable of preventing the exhaust gas from flowing in the reverse direction in the test chamber. Thus, air currents flowing in a region above the engine of the aircraft can be regulated to ensure an air current condition proper for the run-up of the engine of the aircraft.

Preferably, the inclined section has laterally opposite parts respectively extending on the opposite sides of the groove 31 and sloping down toward right and left side wall structures. The flow of the accompanying currents decreases with distance from the groove 31. Therefore, the laterally opposite parts of the inclined section are sloped down toward the right and the left side wall structure, respectively, to prevent the reduction of the velocity of the accompanying currents in the vicinity of the right and the left side wall structures.

Preferably, a reverse flow stopping plate of a width approximately equal to that of the test chamber is suspended from the ceiling of the test chamber so as to extend in front of the vertical tail fin of an aircraft placed in the test chamber. The reverse flow stopping plate prevents the reverse from of the exhaust gas from a back part of the test chamber through an upper region of the test chamber into a front part of the test chamber.

Preferably, a vertical tail fin passing gap that permits the vertical tail fin to pass when carrying the aircraft into or out of the aircraft engine run-up hangar is formed in a middle part, with respect to width, of the reverse flow stopping plate, and the vertical tail fin passing gap can be closed or opened by a reverse flow stopping cover. The vertical tail fin passing gap is opened when the aircraft is carried into or out of the aircraft engine run-up hangar, and is kept closed during the run-up of the engine to prevent the reverse flow of the exhaust gas through the vertical tail fin passing gap.

Preferably, the reverse flow stopping plate is disposed near the back end of the inclined section of the ceiling. Thus, air currents flowing along the inclined section flow backward beyond the reverse flow stopping plate and are prevented from flowing upstream by the reverse flow stopping plate.

Preferably, an air inlet structure through which fresh air can be taken into the building is formed at a position on the roof structure corresponding to a position in front of the groove formed in the inclined section of the ceiling. Since fresh air flows through the air inlet structure into the groove, the exhaust gas is hardly able to flow forward through the groove formed in the inclined section.

Preferably, a pair of current-straightening plates for the run-up of the tail engine of the aircraft are extended down from the opposite side walls of the groove formed in the inclined section of the ceiling to straighten air currents flowing toward the tail engine of the aircraft. Although air currents flowing along the inclined section of the ceiling tend to flow laterally toward the groove and to affect the run-up of the tail engine adversely, the pair of current-straightening plates straightens the air currents laterally flowing toward the tail engine.

Preferably, the current-straightening plates for the run-up of the tail engine are formed from a metal net, a textile net, a perforated plate, a slit plate or an expanded metal. The current-straightening plates of simple construction straighten air currents and absorb sounds.

Preferably, the building of the aircraft engine run-up hangar has right and left side walls respectively having back half sections extended obliquely toward each other such that the distance between the back half sections decreases toward the back. Thus, proper accompanying currents are produced in the entire test chamber, the enhancement of noise by the repetitive reflection of sounds of specific frequencies by the opposite side walls can be prevented and noise can be reduced.

Preferably, sound-absorbing structures are incorporated into the right and the left side wall. The sound-absorbing structures absorb sounds to reduce noise.

Preferably, the exhaust structure has a width substantially equal to that of a back end part of the building. The exhaust structure having a width substantially equal to that of the back end part of the building defines an exhaust passage of a large sectional area. Therefore, the exhaust gas and the accompanying currents can be smoothly discharged and stable, backward air currents can be produced in the test chamber.

Preferably, the exhaust structure is joined to the back end of the building so as to extend over the entire width of the back end of the building. Thus the construction of the exhaust structure can be simplified, the exhaust gas and the accompanying currents can be smoothly discharged and stable, backward air currents can be produced in the test chamber.

Preferably, the exhaust structure has an upward curving or bending passage. The exhaust gas can be smoothly guided so as to be discharged vertically upward.

Preferably, the exhaust structure has main engine exhaust ducts through which exhaust gas discharged from main engines supported on the right and the left main wing of the aircraft is exhausted, and a tail engine exhaust duct through which exhaust gas discharged from the tail engine of the aircraft is exhausted. It is desirable that the exhaust duct is spaced a predetermined distance apart from the engine. The tail engine exhaust duct extends backward beyond the back ends of the main engine exhaust ducts. Thus, the main engine exhaust ducts and the tail engine exhaust duct can be spaced proper distances apart from the main engines and the tail engines, respectively.

Preferably, each of the main engine exhaust ducts has a vertical part vertically rising at the back end of the building. The vertical part of the main engine exhaust duct can be extended along the back end wall of the building and hence the construction thereof can be simplified.

Preferably, the tail engine exhaust duct defines a passage curved or bent obliquely upward toward the back. The exhaust gas can be smoothly guided and can be discharged vertically upward.

Preferably, curved connecting members connect parts of the inclined section of the ceiling extending on the opposite sides of the groove formed in the inclined section, and the opposite side walls of the groove formed in the inclined section, respectively. Air currents laterally flowing along the inclined section toward the groove formed in the inclined section into the tail engine can be straightened by the curved connecting members.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic longitudinal sectional view of an aircraft engine run-up hangar in a preferred embodiment according to the present invention in a vertical plane including the longitudinal axis of the aircraft engine run-up hangar;

FIG. 2 is a schematic sectional view of the aircraft engine run-up hangar shown in FIG. 1 in a vertical plane not including the longitudinal axis of the aircraft engine run-up hangar;

FIG. 3 is a cross-sectional view of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 4 is a cross-sectional view of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 5 is a plan view of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 6 is a sectional view of the aircraft engine run-up hangar shown in FIG. 1 in a horizontal plane;

FIG. 7 is a front elevation of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 8 is a rear elevation of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 9 is a left side elevation of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 10 is table showing data obtained through model experiments conducted to examine the effect of the height of a wind guard structure;

FIG. 11 is a graph showing the data tabulated in the table shown in FIG. 10;

FIG. 12 is a table showing data obtained through model experiments on the open-area ratio of the wind guard structure;

FIG. 13 is a graph showing the data tabulated in the table shown in FIG. 12;

FIG. 14 is a table showing data obtained through model experiments on the intensity of turbulent flow above an engine;

FIG. 15 is a graph showing the data tabulated in the table shown in FIG. 14;

FIG. 16 is a table showing data obtained through model experiments on the position of a current deflecting member;

FIG. 17 is a graph showing the data tabulated in the table shown in FIG. 16;

FIG. 18 is a velocity vector diagram of assistance in explaining air currents in the aircraft engine run-up hangar shown in FIG. 1;

FIG. 19 is a velocity vector diagram of assistance in explaining air currents in an aircraft engine run-up hangar in a comparative example;

FIG. 20 is a sectional plan view of an aircraft engine run-up hangar in a first modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 21 is a longitudinal sectional view of the aircraft engine run-up hangar shown in FIG. 20;

FIG. 22 is across-sectional view of the aircraft engine run-up hangar shown in FIG. 20;

FIG. 23 is a cross-sectional view of the aircraft engine run-up hangar shown in FIG. 20;

FIG. 24 is a front elevation of the aircraft engine run-up hangar shown in FIG. 20;

FIG. 25 is a sectional view of an aircraft engine run-up hangar in a second modification of the aircraft engine run-up hangar shown in FIG. 25 in a horizontal plane;

FIG. 26 is a longitudinal sectional view of the aircraft engine run-up hangar shown in FIG. 25;

FIG. 27 is a longitudinal sectional view of an aircraft engine run-up hangar in a third modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 28 is a longitudinal sectional view of an aircraft engine run-up hangar in a fourth modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 29 is a longitudinal sectional view of an aircraft engine run-up hangar in a fifth modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 30 is a longitudinal sectional view of an aircraft engine run-up hangar in a sixth modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 31 is a longitudinal sectional view of an aircraft engine run-up hangar in a seventh modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 32 is a longitudinal sectional view of an aircraft engine run-up hangar in an eighth modification of the aircraft engine run-up hangar shown in FIG. 1;

FIG. 33 is a longitudinal sectional view of an aircraft engine run-up hangar in a ninth modification of the aircraft engine run-up hangar shown in FIG. 1; and

FIG. 34 is a longitudinal sectional view of an aircraft engine run-up hangar in a tenth modification of the aircraft engine run-up hangar shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 4, an aircraft engine run-up hangar 1 in a preferred embodiment according to the present invention includes a building 4 defining a test chamber 3 in which an aircraft is subjected to an aircraft engine run-up, an entrance structure 5 formed at the front end of the building 4, an air inlet structure 6 through which air is taken into the test chamber, and an exhaust structure 7 through which gases are exhausted from the test chamber 3. In the following description, words, front, back, right, left and such are used for expressing directional and positional attributes as viewed facing the front end of the building 4.

Referring to FIGS. 1 to 9, the building 4 is a building of steel skeleton construction having a front end wall structure 10, a left side wall structure 11, a right side wall structure 12, a back end wall structure 13, and a roof structure 14. The entrance structure 5 extends over the entire width of the front structure 10 and is closed by a large door 15. The large door 15 has a left half door 15 a and a right half door 15 b. Each of the half doors 15 a and 15 b consists of a plurality of separate narrow door members supported on and guided by rails. Each of the half doors 15 a and 15 b may be formed by connecting narrow door members. The left half door 15 a can be moved by a horizontal door moving device of a monorail type, not shown, between an open position beside the inner surface of the left side wall structure 11 and a closing position for closing the left half part of the entrance 5. Similarly, the right half door 15 b can be moved by a horizontal door moving device of a monorail type, not shown, between an open position beside the inner surface of the right side wall structure 12 and a closing position for closing the right half part of the entrance 5.

The air inlet structure 6 is set on a part of the roof structure 14 in a front end part of the building 4. The air inlet structure 6 is isolated from the entrance 5. Air does not need to be taken into the building 4 through the entrance 5 when testing the engine of an aircraft 2 and hence the large door 15 is kept closed during the run-up of the engine. The large door 15 has a thickness approximately equal to that of an ordinary soundproof door. The large door 15 may be moved vertically for closing and opening by a vertical door operating mechanism. This large door 15 does not need any space for storing the half doors 15 a and 15 b in the opposite ends of the front end of the building 4, which is favorable to saving a space necessary for installing the aircraft engine run-up hangar 1.

As shown in FIGS. 1 to 4, the roof of the roof structure 14 of the building 4 is a gable roof sloping down in opposite lateral directions. The roof of the roof structure 14 may be a flat roof. The air inlet structure 6 is disposed in a front end part of the roof structure 14 and extends over the substantially entire width of the building 4. The air inlet structure 6 is disposed above a space in front of the aircraft housed in the building 4 for run-up. An air-permeable wind guard structure 16 is set on the roof structure 14 so as to surround the air inlet of the air inlet structure 6. The wind guard structure 16 reduces the adverse effects of wind, such as the variation of the direction and velocity of wind, and swirling or turbulent flow of air, on air currents flowing through the air inlet structure 6 into the test chamber 3. The wind guard structure 16 has a mean height of 2.0 m or above. Each of the walls of the wind guard structure 16 is a single- or a double-layer structure formed by putting together metal nets having an open-area ratio in the range of 50% to 75%. The walls of the wind guard structure 16 may be formed from a textile net, a perforated plate provided with many small holes, a slit plate provided with many small slits or an expanded metal. A top wind guard 17 is placed on the upper end of the wind guard structure 16 so as to cover the open upper end of the wind guard structure 16 at a level substantially the same as that of the upper end of the wind guard structure 16. The top wind guard 17 is a single-layer structure formed from a metal net having an open-area ratio in the range of 50% to 75% or a double-layer structure formed by putting together metal nets having an open-area ratio in the range of 50% to 75%. The top wind guard 17 may be formed from a textile net, a perforated plate provided with many small holes, a slit plate provided with many small slits or an expanded metal.

The air inlet structure 6 is provided with a current-straightening structure 18 having a predetermined height, i.e., a dimension along the flowing direction of air, in the range of, for example, 4 to 5 m. The current-straightening structure 18 is built by assembling a plurality of vertical plates 18 a in a grid. Each of the plates 18 a is a sound-absorbing panel formed by applying a sound-absorbing material to a corrugated steel plate having rectangular ridges and furrows. The current-straightening structure 18 has a current-straightening function to straighten air currents flowing down through the air inlet structure 6 and a noise suppressing function to suppress run-up noise generated in the building 4.

A first current-straightening member 21 is attached to the lower end of the current-straightening structure 18 so as to cover the lower end entirely. The first current-straightening member 21 is formed from a metal net or a textile net having an open-area ratio in the range of 40% to 70%. Flat guide members 18 b formed by processing a steel plate and attached to the lower edges of the lateral plates of the current-straightening structure 18 are placed in a middle part with respect to the width of the upper surface of the first current-straightening member 21. The first current-straightening member 21 may be a perforated plate provided with many small holes, a slit plate provided with many small slits or an expanded metal.

A single current deflecting member 20 is fixed to the lower end of the current-straightening structure 18. The current deflecting member 20 has a predetermined height. A current-straightening space 19 of a predetermined height in the range of, for example, 4 to 5 m is defined under the current-straightening structure 18. A second current-straightening member 22 for straightening air currents flowing through the air inlet structure 6 into the building 4 is disposed so as to define the bottom of the current-straightening space 19. The second current-straightening member 22 is formed from a metal net or a textile net having an open-hole ratio in the range of 40% to 70%. The second current-straightening member 22 may be a perforated plate provided with many small holes, a slit plate provided with many small slits or an expanded metal.

A plurality of vertical third current-straightening members 23 are arranged in a grid in the current-straightening space 19 so as to define vertical passages for air currents. The third current-straightening members 23 are metal nets or textile nets having an open-hole ratio in the range of 40% to 70%. The third current-straightening members 23 may be perforated plates provided with many small holes, slit plates provided with many small slits or expanded metals. A fourth current straightening member 24 is disposed behind the current deflecting member 20 so as to extend between a position near a lower end part of the current deflecting member 20 to the ceiling of the building 4 to straighten air currents flowing through a back part of the air inlet structure 6 into the building 4. The fourth current straightening member 24 is formed from a metal net or a textile net having an open-area ratio in the range of 40 to 70%. The fourth current-straightening member 24 may be formed from a perforated plate provided with many small holes, a slit plate provided with many small slits or an expanded metal.

The current deflecting member 20 will be described. As shown in FIGS. 1 to 3, the current deflecting member 20 deflects air currents flowing through the air inlet structure 6 into the building 4 and guides the same so as to flow substantially horizontally toward the aircraft 2. The current deflecting member 20 is a plate having a substantially J-shaped cross section and extending over the substantially entire width of the building 4. The current deflecting member 20 is disposed at or near a position at a distance in the range of {fraction (3/14)} to {fraction (3/7)} of the length of the air inlet structure 6 from the back end of the air inlet structure 6. The upper end of the current deflecting member 20 is fixed to the lower edge of the vertical plate 18 a extending along the width of the current-straightening structure 18 and is held by a truss 25 connected to the roof structure 14 of the building 4.

The current deflecting member 20 has a vertical part 20 a, and a horizontal part 20 b extending horizontally forward. The horizontal part 20 b is at a level somewhat higher than those of the fuselage 2 a and the horizontal stabilizer of the largest one of aircrafts 2 that can be received in the test chamber 3 to avoid interference between the horizontal part 20 b and the aircraft 2 when carrying the aircraft 2 into or out of the aircraft engine run-up hangar 1. The current deflecting member 20 may be disposed at any suitable position other than the aforesaid position. For example, the current deflecting member 20 may be disposed at a position at a distance in the range of about B/8 to B/2, where B is the length of the air inlet structure 6, from the back end of the air inlet structure 6. Lower parts of the vertical part 20 a of the current deflecting member 20 may be inclined at suitable angles to a horizontal plane, and the horizontal part 20 b may be slightly inclined.

As shown in FIG. 3, a vertical tail fin passing gap 26 that permits the vertical tail fin 2 b of an aircraft 2 to pass when carrying the aircraft 2 into or out of the aircraft engine run-up hangar 1 is formed in a middle part, with respect to the width, of the current deflecting member 20, and the vertical tail fin passing gap 26 is closed by a reverse flow stopping cover 27. The reverse flow stopping cover 27 is a roll-up shutter that can be rolled up to open the vertical tail fin passing gap 26 by a driving device, not shown, held on the roof structure 14. The reverse flow stopping cover 27 is opened when carrying the aircraft 2 into or out of the aircraft engine run-up hangar 1, and is closed during run-up. The reverse flow stopping cover 27 may include a pair of sliding doors that can be moved in opposite directions, respectively by a driving device.

As shown in FIGS. 1 and 2, most part of the ceiling of the building 4 is an inclined section 30. The inclined section 30 straightens air currents flowing through the test chamber to make accompanying currents accompanying the flow of an exhaust gas emitted from the engine of the aircraft 2 during run-up, and air around the accompanying currents to flow regularly toward the back of the test chamber 3. As shown in FIG. 4, a groove 31 is formed in a middle part, with respect to the width, of the inclined section 30 to permit the vertical tail fin 2 b of the aircraft 2 to pass when the aircraft 2 is carried into or out of the test chamber 3. The opposite side walls of the groove 31 are formed of plates.

The inclined section 30 of the ceiling extends between a position near the back end of the air inlet structure 6 and a position in front of the vertical tail fin 2 b of the aircraft 2 placed in the test chamber 3 and slopes down gently toward the back. The inclined section 30 has laterally opposite parts respectively extending on the opposite sides of the groove 31 and sloping down toward the right side wall structure 12 and the left side wall structure 11 in parallel to the roof of the roof structure 14. The flow of the accompanying currents decreases with distance from the groove 31. Therefore, the laterally opposite parts of the inclined section 30 are sloped down toward the right side wall structure 12 and the left side wall structure 11, respectively, to prevent the reduction of the velocity of the accompanying currents in the vicinity of the right side wall structure 12 and the left side wall structure 11.

Referring to FIGS. 1, 2 and 4, a reverse flow stopping plate 32 of a width approximately equal to that of the test chamber 3 is suspended from the ceiling of the test chamber 3 so as to extend in front of the vertical tail fin 2 b of the aircraft 2 placed in the test chamber 3. The reverse flow stopping plate 32 has a J-shaped cross section and is disposed at a position at or near the back end of the inclined section 30. The upper end of the reverse flow stopping plate 32 is fixed to the roof structure 14 and the lower end of the same is fixed to the back end of the inclined section 30 of the ceiling. A vertical tail fin passing gap 33 that permits the vertical tail fin 2 b to pass when carrying the aircraft 2 into or out of the aircraft engine run-up hangar 1 is formed in a middle part, with respect to width, of the reverse flow stopping plate 32. The vertical tail fin passing gap 33 can be closed or opened by laterally moving a pair of covers 34, i.e., doors, by a driving device, not shown. The vertical tail fin passing gap 33 is opened when the aircraft is carried into or out of the aircraft engine run-up hangar 1, and is kept closed during run-up. A roll-up shutter that can be rolled up may be used instead of the pair of covers 34.

A pair of current-straightening plates 35 are extended down from the opposite side walls of the groove 31 to straighten air currents flowing toward a tail engine 2 e. The current-straightening plates 35 may be metal nets, textile nets, perforated plates provided with many small holes, slit plates provided with many small slits or expanded metals.

Referring to FIGS. 5 and 6, the opposite side walls 36 of the test chamber 3 are provided with a sound-absorbing structure formed by attaching a sound-absorbing member to a plate. Back half sections 36 a of the side walls 36 are extended obliquely toward each other such that the distance between the back half sections 36 a decreases toward the back to produce proper accompanying currents in the entire test chamber 3 and to prevent the enhancement of noise by the repetitive reflection of sounds of specific frequencies by the opposite side walls 36.

Referring to FIGS. 1, 2, 5 and 6, the exhaust structure 7 is disposed in a back end part of the building 4 so as to communicated with the test chamber 3. The exhaust structure 7 has a width substantially equal to that of the back end part of the building 4. The exhaust structure has a back section that extends upward. The exhaust structure 7 has main engine exhaust ducts 37 through which exhaust gas discharged from main engines 2 d supported on the right and the left main wing 2 c of the aircraft 2 is exhausted, and a tail engine exhaust duct 38 through which exhaust gas discharged from the tail engine 2 e of the aircraft 2 is exhausted. The tail engine exhaust duct 38 extends backward beyond the back ends of the main engine exhaust ducts 37. An exhaust opening 37 a is formed at the upper end of each of the main engine exhaust ducts 37 to discharge the exhaust gas vertically upward, and an exhaust opening 38 a is formed at the upper end of the tail engine exhaust duct 38 to discharge the exhaust gas vertically upward. Each main engine exhaust duct 37 has a sharply curved section 39, and a vertical section 40 extending vertically upward from the curved section 39 in a back part of the building 4. The tail engine exhaust duct 38 has a curved section 41 gently curving upward toward the back. The lower walls of the curved sections 39 and 41 are perforated. Silencing spaces 42 and 43 are formed behind the lower walls of the curved sections 39 and 41, respectively, and sound-absorbing members 44 and 45 are placed behind the lower walls of the curved sections 39 and 41, respectively.

Effects and operations of the aircraft engine run-up hangar 1 will be explained. Since the air inlet structure 6 is set on the front end part of the roof structure 14 of the building 4, the large door 15 which is opened when carrying the aircraft 2 into or out of the aircraft engine run-up hangar 1 does not need to be provided with any air inlet, and hence the large door 15 may be of simple construction similar to that of an ordinary soundproof door. Therefore, any large space is not necessary for moving and storing the large door 15, which is favorable to saving space necessary for installing the aircraft engine run-up hangar 1. The installation of the air inlet structure 6 on the roof structure 14 facilitates incorporating various current-straightening means into the air inlet structure 6. Since the air inlet structure 6 is disposed on the front end part of the roof structure 14 corresponding to the front end part of the building 4, air currents introduced through the air inlet structure 6 into the test chamber 3 tend to flow vertically downward, to impinge on the floor of the test chamber 3, to be disturbed and to induce reverse currents in the test chamber 3. However, the current deflecting member 20 disposed near the lower end of the air inlet structure 6 deflects the air currents so that the air currents flow substantially horizontally toward the aircraft 2 and do not impinge on the floor of the test chamber 3. Thus, scarcely disturbed, scarcely swirling, stable air currents flow into the engine of the aircraft 2 to ensure proper run-up conditions.

Since the exhaust structure 7 communicating with the test chamber 3 and extending backward from the back end of the test chamber 3 and then upward is disposed in the back end part of the building 4, the exhaust structure 7 does not need to be moved longitudinally when the types of aircrafts are changed, and air taken into the test chamber 3 is discharged upward from the back end part of the building 4. Therefore, space behind the building 4 for discharging air can be reduced, which is favorable to saving space for installing the aircraft engine run-up hangar 1.

The air-permeable wind guard structure 16 set on the roof structure 14 so as to surround the air inlet of the air inlet structure 6 reduces the adverse effects of wind, such as the variation of the direction and velocity of wind, and swirling or turbulent flow of air, on air currents flowing through the air inlet structure 6 into the test chamber 3, so that the distribution of the velocities of air currents in the air inlet of the air inlet structure 6 can be uniformed. Since the air inlet structure 6 is provided with the current-straightening structure 18 provided with the plurality of plates 18 a arranged in a grid or a honeycomb so as to define vertical passages, air currents flowing through the air inlet structure 6 are straightened so as to flow regularly downward. Since the plurality of plates 18 a arranged in a grid or a honeycomb are capable of absorbing sounds, run-up noise emitted by the engine during run-up in the building 4 can be controlled by the current-straightening structure 18 and emission of noise through the air inlet structure 6 can be reduced. Since the current-straightening structure 18 incorporated into the air inlet structure 6 opens upward, the run-up noise diffuses upward into the atmosphere and the level of the run-up noise propagating around the building 4 can be reduced. The first current-straightening member 21 straightens the air currents flowed through the current-straightening structure 18 still further.

Since the current-straightening space 19 of a predetermined height is formed under the current-straightening structure 18, and the second current-straightening member 22 is disposed in a lower end part of the current-straightening space 19, air currents flowing at different velocities below the plurality of plates 18 a of the current-straightening structure 18 can be uniformed and small eddies produced in the air currents can be eliminated in the current-straightening space 19, and the air currents straightened in the current-straightening space 19 is straightened further by the second current-straightening member 22.

Since the plurality of third current-straightening members 23 are disposed in the current-straightening space 19 in a grid or in parallel to each other so as to extend in the direction of the air currents, the straightening of the air currents in the current-straightening space 19 can be promoted. Since the air inlet structure 6 is disposed at a position on the front end part of the roof structure 14 of the building 4 corresponding to a position in front of the aircraft 2 housed in the building, the air currents introduced through the air inlet structure 6 can be deflected by the current deflecting member 20 so as to flow in a substantially horizontal direction toward the aircraft 2.

Since the air inlet structure 6 has a width nearly equal to that of the building 4, the air inlet structure 6 is able to define an air passage of a large sectional area, to make air currents flow at low velocities so that the air currents can be satisfactorily straightened and to suppress the flow of air currents in lateral directions in the test chamber 3.

Since the current deflecting member 20 is a plate having a substantially J-shaped cross section, air currents on the back side of the current deflecting member 20 are deflected backward by the guiding effect of the current deflecting member 20, and air currents on the front side of the current deflecting member 20 are deflected backward by the Coanda effect. Since the current deflecting member 20 is disposed in a region around a position at a distance equal to {fraction (3/14)} to {fraction (3/7)} of the length of the air inlet structure 6 from the back end of the air inlet structure 6, air currents flow on the front and the back side of the current deflecting member 20, and the current deflecting member 20 exercises both the guiding action and the Coanda effect with reliability. The range {fraction (3/14)} to {fraction (3/7)} was determined empirically, which will be described later.

Since the fourth current-straightening member 24 is extended from a position near the lower end of the current deflecting member 20 to the ceiling of the building 4 on the back side of the current deflecting member 20, air currents flowing on the back side of the current deflecting member 20 can be straightened by the fourth current-straightening member 24. Since the vertical tail fin passing gap 26 that permits the vertical tail fin 2 b of the aircraft 2 to pass when carrying the aircraft 2 into or out of the building 4 is formed in a middle part of the current deflecting member 20, and the vertical tail fin passing gap 26 is covered with the removable reverse flow stopping cover 27, the aircraft 2 can be carried into or out of the building 4 even if the lower edge of the current deflecting member 20 is at a level below that of the tip of the vertical tail fin 2 b by moving the reverse flow stopping cover 27 away from the vertical tail fin passing gap 26 to open the vertical tail fin passing gap 26 so that the vertical tail fin 2 b is able to pass through the vertical tail fin passing gap 26. The current deflecting member 20 is able to function normally for deflecting air currents without being affected by the vertical tail fin passing gap 26 because the vertical tail fin passing gap 26 is closed by the reverse flow stopping cover 27 during run-up. Since the wind guard structure 16 has an open-area ratio in the range of 50% to 75%, the wind guard structure 16 provides a low resistance against the passage of air currents and exercises a protective function against wind satisfactorily. Since the wind guard structure 16 has a mean height of 2.0 m or above, the wind guard structure 16 is able to exercise the protective function satisfactorily. Since the air-permeable, upper wind guard 17 is disposed on the upper end of the wind guard structure 16 at a level substantially equal to that of the upper end of the wind guard structure 16 so as to cover the upper end of the air inlet structure 6. The upper wind guard 17 reduces the effect of wind and wind direction on air currents flowing therethrough into the air inlet structure 6 and uniforms the velocity of the air currents in the entire region of the air inlet structure 6.

The current-straightening structure 18 having a predetermined height along the direction of the air current has a satisfactory current-straightening ability. Since the plates of the current-straightening structure 18 are formed of a sound-absorbing material, run-up noise emitted by the engine during run-up in the building 4 can be effectively absorbed by the sound-absorbing plates of the current-straightening structure 18 and emission of noise through the air inlet structure 6 of the building 4 can be reduced. Since the current-straightening members 21, 22, 23 and 24 are metal nets, textile nets, perforated plates, slit plates or expanded metals, and have an open-area ration in the range of 40% to 70%, The current-straightening plates 21, 22, 23 and 24 are simple in construction, do not provide excessively large resistance against the flow of air currents, and have a satisfactory current-straightening ability.

Since the inclined section 30 for straightening air currents flowing through the test chamber 3 is formed in a part of the ceiling of the building 4, and the groove 31 is formed in a middle part, with respect to the width, of the inclined section 30 to permit the vertical tail fin 2 b of the aircraft 2 to pass when the aircraft 2 is carried into or out of the test chamber 3, the inclined section 30 can be formed at a level far lower than that of the vertical tail fin 2 b of the aircraft 2 so as to slope down toward the back, accompanying currents accompanying the flow of the exhaust gas emitted from the engine of the aircraft 2, and air around the accompanying currents can be made to flow regularly toward the back of the test chamber 3, the accompanying currents can be produced so as to prevent the generation of reverse currents, air currents on the upstream side of the engines 2 d and 2 e of the aircraft 2 can be straightened, and proper run-up conditions can be ensured for the run-up of the engines 2 d and 2 e of the aircraft 2.

The inclined section 30 of the ceiling has the laterally opposite parts respectively extending on the opposite sides of the groove 3 and sloping down toward the right side wall structure 12 and the left side wall structure 11 in parallel to the roof of the roof structure 14. The flow of the accompanying currents decreases with distance from the groove 31. Therefore, the laterally opposite parts of the inclined section 30 are sloped down toward the right side wall structure 12 and the left side wall structure 11, respectively, to prevent the reduction of the velocity of the accompanying currents in the vicinity of the right side wall structure 12 and the left side wall structure 11. Since the reverse flow stopping plate 32 of a width approximately equal to that of the test chamber 3 is disposed so as to extend in front of the vertical tail fin 2 b of the aircraft 2 placed in the test chamber 3, the reverse flow of the exhaust gas through an upper space in the back part of the test chamber 3 toward the front of the test chamber can be prevented by the reverse flow stopping plate 32.

The vertical tail fin passing gap 33, that permits the passage of the vertical tail fin 2 b when carrying the aircraft 2 into or out of the aircraft engine run-up hangar 1, is formed in a middle part, with respect to width, of the reverse flow stopping plate 32, and the vertical tail fin passing gap 33 can be closed or opened by laterally moving the pair of covers 34 by the driving device. The vertical tail fin passing gap 33 is opened when the aircraft is carried into or out of the aircraft engine run-up hangar 1, and is kept closed during run-up. Thus the reverse flow of the exhaust gas through the vertical fin passing gap 33 can be prevented. Since the reverse flow stopping plate 32 is disposed near the back end of the inclined section 30 of the ceiling, the air currents flowing along the inclined section 30 flow backward beyond the reverse flow stopping plate 32 and is prevented from flowing upstream by the reverse flow stopping plate 32.

The pair of current-straightening plates 35 are extended down from the opposite side walls of the groove 31 to straighten air currents flowing toward the tail engine 2 e. Air currents flowing along the inclined section 30 of the ceiling flow laterally toward the groove 31 and are sucked into the tail engine 2 e to affect the operation of the tail engine 2 e adversely. The pair of current-straightening plates 35 straightens the air currents laterally flowing toward the tail engine 2 e. The current-straightening plates 35 are metal nets, textile nets, perforated plates, slit plates or expanded metals.

Since the back half sections 36 a of the opposite side walls 36 of the test chamber 3 are extended obliquely toward each other such that the distance between the back half sections 36 a decreases toward the back, proper accompanying currents can be produced in the entire test chamber 3 and the enhancement of sound pressure generated in the air current by the repetitive reflection of sounds of specific frequencies by the opposite side walls 36 can be suppressed. The sound-absorbing structures incorporated into the opposite side walls 36 of the test chamber 3 absorb and reduce noise.

Since the exhaust structure 7 having a width substantially equal to that of the back end part of the building 4 defines an exhaust passage of a large sectional area, the exhaust gas and the accompanying currents can be smoothly discharged and stable, backward air currents can be produced in the test chamber 3.

It is desirable that the engines 2 d and 2 e are spaced predetermined distances apart, respectively, from the exhaust structure 7. The exhaust structure 7 has the wide main engine exhaust ducts 37 through which exhaust gas discharged from the main engines 2 d supported on the right and the left main wing 2 c of the aircraft 2 is exhausted, and the narrow tail engine exhaust duct 38 through which exhaust gas discharged from the tail engine 2 e of the aircraft 2 is exhausted. The main engine exhaust ducts 37 and the tail engine exhaust duct 38 can be spaced proper distances apart from the main engines 2 d and the tail engines 2 e, respectively, by disposing the tail engine exhaust duct 38 on the back side of the main engine exhaust ducts 37.

Since each main engine exhaust duct 37 has the curved section 39 capable of sound absorption, the flow of the exhaust gas can be smoothly guided, noise can be absorbed and the exhaust gas can be discharged vertically upward. The main engine exhaust duct 37 has the vertical section 40 extending vertically upward from the curved section 39 in the back end part of the building 4. The vertical section 40 can be disposed along the back end wall structure 13 and hence can be formed in simple construction. The tail engine exhaust duct 38 has the sound-absorbing curved section 41 gently curving upward toward the back. Thus, the flow of the exhaust gas discharged from the tail engine 2 e can be smoothly guided, noise can be absorbed and the exhaust gas can be discharged vertically upward.

Results of model experiments conducted to demonstrate the abilities of the current-straightening members included in the aircraft engine run-up hangar 1 will be explained with reference to FIGS. 10 to 19.

FIGS. 10 and 11 show data obtained through model experiments conducted to examine the effect of the height of the wind guard structure 16. The term “height of the wind guard structure” signifies the height of the top of the wind guard structure 16 from the ridge of the roof structure 14. In FIGS. 10 and 11, “total pressure reduction” is the difference between the atmospheric pressure and a measured total pressure at a position immediately in front of the air inlet of the main engine, and “total pressure reduction ratio” is the ratio of a total pressure reduction to that when the height of the wind guard structure 16 is 0 m. The wind guard structure 16 was formed by putting together two metal nets having an open-area ratio φ=70%. As obvious from FIGS. 10 and 11, the greater the height of the wind guard structure 16, the smaller is the total pressure drop ratio and the smaller the swirling and turbulent flows in the air currents. Thus, it is desirable that the height (mean height) of the wind guard structure 16 is 2 m or above.

FIGS. 12 and 13 show data obtained through experiments conducted to examine the effect of the open-area ratio φ of the walls of the wind guard structure 16. A sample wind guard structure having walls each formed of a single metal net having an open-area ratio of 70%, a first sample wind guard structure having walls each formed of a single metal net having an open-area ratio of 70%, a second sample wind guard structure having walls each formed by putting together two metal nets having an open-area ratio of 70%, and a third sample wind guard structure having walls each formed by putting together three metal nets having an open-area ratio of 70% were subjected to the experiments. It is known from the results of the experiments that the protective ability of the wind guard structure 16 is low when the open-area ratio of the wind guard structure 16 is either excessively large or excessively small, and that a desirable range for the open-area ratio of the wind guard structure 16 is 50% to 75%.

FIGS. 14 and 15 show data obtained through experiments conducted to examine the effect of the open-area ratio φ of the second current-straightening member 22. Five different sample second current-straightening members were subjected to the experiments. It is known from the results of the experiments that the current-straightening ability of the second current-straightening member 22 is low when the open-area ratio φ of the second current-straightening member 22 is either excessively large or excessively small, and that a desirable range for the open-area ratio of the second current-straightening member 22 is 40% to 70%. The open-area ratio of a current-straightening member formed by putting together two metal net having an open-area ratio φ=70% is about 50%.

FIGS. 16 and 17 show data obtained through experiments conducted to examine the effect of the position of the current deflecting member 20 on the total pressure reduction ratio. In FIGS. 16 and 17, the position (b) of the current deflecting member 20 is represented by the distance between the current deflecting member 20 and the back end of the air inlet structure 6 to the length B of the air inlet structure 6. For example, a position b={fraction (1/7)} is at a distance equal to B/7 from the back end of the air inlet structure 6. In FIGS. 16 and 17, “pressure reduction” is the difference between the atmospheric pressure and a measured total pressure at a position immediately in front of the air inlet of the engine in the rest chamber 3, and “total pressure reduction ratio” is the ratio of a total pressure reduction ratio to that when the current deflecting member 20 is located at the position b=0, i.e., at the back end of the air inlet structure 6. It is known from FIGS. 16 and 17 that it is most desirable that the current deflecting member 20 is disposed at a position at a distance in the range of 3B/14 to 3B/7 from the back end of the air inlet structure 6.

FIGS. 18 and 19 are simplified conceptional streamline diagrams indicating velocity vectors of air currents obtained by analyzing air currents in the aircraft engine run-up hangar 1 by a finite element method using a numerical fluid analyzing program. FIG. 18 is a streamline diagram in the aircraft engine run-up hangar 1 provided with the current deflecting member 20, and FIG. 19 is a streamline diagram in an aircraft engine run-up hangar in a comparative example not provided with any member corresponding to the current deflecting member 20. Curves A and B in FIG. 18 and curves C and D in FIG. 19 are manually drawn curves indicating boundaries between air currents flowing into the main engine 2 d and those not flowing into the main engine 2 d. It is known from FIGS. 18 and 19 showing velocity vectors of air currents that air currents flowing upstream from a region behind the main engine 2 d flow into the main engine 2 d in the aircraft engine run-up hangar in the comparative example not provided with any member corresponding to the current deflecting member 20, and air currents flow upstream scarcely from a region behind the main engine 2 d into the main engine 2 d.

Aircraft engine run-up hangars in modifications of the foregoing aircraft engine run-up hangar 1 embodying the present invention will be described with reference to FIGS. 20 to 34, in which parts like or corresponding to those of the aircraft engine run-up hangar in the first embodiment are denoted by the same reference characters and the description thereof will be omitted.

(1) The reverse flow stopping cover 27 for closing the vertical tail fin passing gap 26 shown in FIG. 1 may be omitted. When the reverse flow stopping cover 27 is omitted, a pair of vertical current-straightening plates 28 are extended longitudinally on the opposite sides of the vertical tail fin passing gap 26 of the current deflecting member 20 as shown in FIG. 34. The current-straightening plates 28 may be steel plates, perforated plates provided with many small holes, or slit plates provided with many small slits. The pair of current-straightening plates 28 suppress the generation of swirling or turbulent flows at the edges of the current deflecting member 20 defining the vertical tail fin passing gap 26.

(2) In an aircraft engine run-up hangar 1A shown in FIGS. 20 to 24, a roof structure 14 included in a building 4 and supporting an air inlet structure 6 slopes down scarcely toward the eaves. An eaves current-straightening structure 50 resembling eaves is formed in parts of the eaves of the roof structure 14 of the building 4 corresponding to the periphery of the air inlet structure 6 to reduce the adverse effect of wind that flows upward along the front end wall and the opposite side walls of the building 4. A plurality of current deflecting members 51, for example, six current deflecting members 51 having a J-shaped cross section are formed integrally with a plurality of laterally extended plates included in a current-straightening structure 18 so as to extend downward from the lower ends of the laterally plates. The current deflecting members 51 nearer to the front end wall of the building 4 are longer than those farther from the front end wall of the building 4.

The ceiling of the building 4 has an inclined section 30 provided with a groove, and a vertical part 30 a is formed at the front end of an inclined section 30 such that the vertical part 30 a serves as a current deflecting member at the back end of the air inlet structure 6. The ceiling has a horizontal section 30 b extending backward from the back end of the inclined section 30 to an exhaust duct. Thus there is no possibility that the exhaust gas flows upstream. Although the aircraft engine run-up hangar 1A is provided with a movable reverse flow stopping member for c closing the groove in the inclined section 30 of the ceiling, the aircraft engine run-up hangar 1A is not provided with any member corresponding to the reverse flow stopping plate 32.

The building 4 has parallel right and left side walls 52. An exhaust structure 53 has two main engine exhaust ducts 53 a and a tail engine exhaust duct 53 b having the same shape in side elevation. The exhaust structure 53 has a width equal to that of a back end part of the building 4. The exhaust structure has a gently curved passage 53 c curving gradually upward toward the back and having an exhaust opening 53 d opening vertically upward. Curved connecting members 71 connect parts of the inclined section 30 of the ceiling extending on the opposite sides of the groove formed in the inclined section 30 and the opposite side walls of the groove formed in the inclined section 30, respectively. Air currents flowing along the inclined section 30 and flowing laterally through the groove formed in the inclined section 30 into the tail engine are straightened by the curved connecting members 71.

The plurality of current deflecting members 51 have an excellent current deflecting ability. Since the roof structure 14 is sloped down scarcely toward the eaves, the air inlet opening of the air inlet structure 6 is substantially horizontal and hence the velocities of air currents can be easily distributed uniformly over the entire air inlet opening of the air inlet structure 6. The exhaust structure 53, and the right side wall structure 12 and the left side wall structure 11 of the building 4 are simple in construction.

(3) An aircraft engine run-up hangar 1B shown in FIGS. 25 and 26 is provided with a plurality of current deflecting members 51 similar to those of the aircraft engine run-up hangar 1A, and a reverse flow stopping plate 32 disposed at a position corresponding to the back end of an inclined section 30 of a ceiling included in a building 4. A groove formed in the inclined section 30 is closed by a reverse flow stopping cover 54. The opposite side wall structures of the building 4 are the same as those of the aircraft engine run-up hangar 1. An exhaust structure 53 included in the aircraft engine run-up hangar 1B is substantially similar to that of the aircraft engine run-up hangar 1A.

(4) The plurality of current deflecting members may be replaced with a plurality of curved guide members 55 longitudinally arranged at predetermined intervals such that the curved guide members 55 nearer to the front end of the building 4 are at lower levels as shown in FIG. 27. The curved guide members 55 may be replaced with inclined flat guides members or vertical flat guide members.

(5) Referring to FIG. 28, a building 4 including a ceiling similar to that of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24 and having an inclined section 30 and a horizontal section 30 b, and an exhaust structure 53 similar to that of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24 is provided with a current deflecting member 20 similar to that of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24.

(6) Referring to FIG. 29, a building 4 including a ceiling similar to that of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24 and having an inclined section 30 and a horizontal section 30 b, and an exhaust structure 53 similar to that of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24 is provided with a current deflecting member 20 similar to that of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24, and a pair of current straightening plates 28 similar to those of the aircraft engine run-up hangar 1A mentioned in (1) and extended longitudinally on the opposite sides of a vertical tail fin passing gap 26 so as to cover the side edges of the current deflecting member 20.

(7) Referring to FIG. 30, an aircraft engine run-up hangar 1B has a ceiling similar to that of the aircraft engine run-up hangar 1B shown in FIGS. 25 and 26, and two current deflecting members 56 longitudinally arranged at an interval and each having a J-shaped cross section.

(8) Referring to FIG. 31, an aircraft engine run-up hangar 1A similar to that shown in FIGS. 20 to 24 has an inclined ceiling 30A having an inclined section 30 sloping down backward and extending to an exhaust structure 53.

(9) Referring to FIG. 32, an aircraft engine run-up hangar 1A similar to that shown in FIGS. 20 to 24 is provided with a single current deflecting member 57 having a substantially S-shaped cross section instead of the current deflecting members 51 of the aircraft engine run-up hangar 1A shown in FIGS. 20 to 24.

(10) Referring to FIG. 33, a current deflecting structure 20A employed instead of the current deflecting member 20 includes a substantially vertical deflecting member 58, a curved flap 60 disposed below the deflecting member 58 such that a gap 59 is formed between the lower edge of the deflecting member 58 and the upper edge of the flap 60, and a curved flap 62 disposed below the curved flap 60 such that a gap 61 is formed between the lower edge of the curved flap 60 and the upper edge of the curved flap 62. The curved flaps 60 and 62 suppress the separation of air currents from the current deflecting structure 20A, the generation of whirling air currents and turbulent air currents to ensure an air current condition suitable for run-up.

(11) Referring to FIG. 34, an aircraft engine run-up hangar 1 similar to the aircraft engine run-up hangar 1 shown in the preferred embodiment, may be provided with an air inlet structure 63 in a roof structure 14 included in a building 4 to introduce fresh air into a front section of a groove 31. Air currents flowing through the air inlet structure 63 into the groove 31 suppress the reverse flow of the exhaust gas into the groove 31.

As apparent from the foregoing description, the present invention has the following effects.

Since the air inlet structure is disposed on the front end part of the roof structure corresponding to a front end part of the building, the large door for closing a large opening through which the aircraft is carried into or out of the building does not need to be provided with any air inlet structure, and the large door may be of simple construction similar to that of an ordinary soundproof door. Therefore any space for moving and storing the large door is not necessary, which is favorable to saving space necessary for installing the aircraft engine run-up hangar and is convenient in incorporating various current-straightening means into the air inlet structure. Since the exhaust structure is connected to the rear end part of the building so as to form the exhaust passage extending obliquely upward from the back end of the building, any work for moving an exhaust duct is not necessary when aircrafts are changed. Since air in the test chamber is discharged upward through the back end part of the building, the exhaust structure has a comparatively short length and needs a comparatively small space for installation behind the building, which is favorable to saving space necessary for installing the aircraft engine run-up hangar.

Since the ceiling has the inclined section sloping down backward and the groove is formed in a middle part, with respect to the width, of the inclined section to permit the vertical tail fin of an aircraft to pass when the aircraft is carried into or out of the test chamber, the inclined section can be extended in a region far below the tip of the vertical tail fin, the inclined section sloping down backward controls the accompanying currents accompanying the current of the exhaust gas so as to flow regularly backward to produce the accompanying currents capable of preventing the exhaust gas from flowing in the reverse direction in the test chamber. Thus, air currents flowing in a region above the engine of the aircraft can be regulated to ensure an air current condition proper for the run-up of the engine of the aircraft.

Since the inclined section has the laterally opposite parts respectively extending on the opposite sides of the groove and sloping down toward the right and the left side wall structure, the reduction of the velocity of the accompanying currents in the vicinity of the right and the left side wall structures can be prevented.

The reverse flow stopping plate prevents the reverse flow of the exhaust gas from a back part of the test chamber through the upper region of the test chamber into a front part of the test chamber.

Since the vertical tail fin passing gap that permits the vertical tail fin to pass when carrying the aircraft into or out of the aircraft engine run-up hangar is formed in a middle part, with respect to width, of the reverse flow stopping plate, interference between the reverse flow stopping plate and the vertical tail fin of the aircraft can be prevented when the aircraft is carried into or out of the aircraft engine run-up hangar, and the reverse flow of the exhaust gas through the vertical tail fin passing gap can be prevented by keeping the vertical tail fin passing gap closed by the reverse flow stopping cover during the run-up of the engine.

Since the reverse flow stopping plate is disposed near the back end of the inclined section of the ceiling, air currents flowing along the inclined section flow backward beyond the reverse flow stopping plate and is prevented from flowing upstream by the reverse flow stopping plate.

Since the air inlet structure through which fresh air can be taken into the building is formed at a position on the roof structure corresponding to a position in front of the groove formed in the inclined section of the ceiling and fresh air flows through the air inlet structure into the groove, the exhaust gas is hardly able to flow forward through the groove formed in the inclined section.

Since the pair of current-straightening plates for the run-up of a tail engine of the aircraft are extended down from the opposite side walls of the groove formed in the inclined section of the ceiling to straighten air currents flowing toward the tail engine of the aircraft, air currents laterally flowing toward the tail engine can be straightened.

Since the current-straightening plates for the run-up of the tail engine is formed from a metal net, a textile net, a perforated plate, a slit plate or an expanded metal, the current-straightening plates is simple in construction and is capable of straightening air currents.

Since the building of the aircraft engine run-up hangar has the right and the left side wall respectively having the back half sections extended obliquely toward each other such that the distance between the back half sections decreases toward the back proper accompanying currents can be produced in the entire test chamber, and generation of noise in the test chamber can be reduced.

Since the sound-absorbing structures are incorporated into the right and the left side wall, the sound-absorbing structures absorb sounds and reduce generation of noise in the test chamber.

Since the exhaust structure has a width substantially equal to that of a back end part of the building, the exhaust structure defines an exhaust passage of a large sectional area. Therefore, the exhaust gas and the accompanying currents can be smoothly discharged, and stable, backward air currents can be produced in the test chamber.

Since the exhaust structure is joined to the back end of the building so as to extend over the entire width of the back end of the building, the construction of the exhaust structure can be simplified, the exhaust gas and the accompanying currents can be smoothly discharged and stable, backward air currents can be produced in the test chamber.

Since the exhaust structure has the upward curving passage, the exhaust gas can be smoothly guided so as to be discharged vertically upward.

Since the exhaust structure has the main engine exhaust ducts through which exhaust gas discharged from the main engines supported on the right and the left main wing of the aircraft is exhausted, and the tail engine exhaust duct through which exhaust gas discharged from the tail engine of the aircraft is exhausted, the main engine exhaust ducts and the tail engine exhaust duct can be spaced proper distances apart from the main engines and the tail engines, respectively.

Since each of the main engine exhaust ducts have the vertical part vertically rising at the back end of the building, the vertical part of the main engine exhaust duct can be extended along the back end wall of the building and hence the construction thereof can be simplified.

Since the tail engine exhaust duct defines the passage curved obliquely upward toward the back, the exhaust gas can be smoothly guided and can be discharged vertically upward.

Since the curved connecting members connect parts of the inclined section of the ceiling extending on the opposite sides of the groove formed in the inclined section, and the opposite side walls of the groove formed in the inclined section, respectively, air currents laterally flowing along the inclined section toward the groove formed in the inclined section into the tail engine can be straightened by the curved connecting members.

Although the invention has been described in its preferred embodiments with a certain degree of particularity, it is obvious to those skilled in the art that many changes and variations are possible therein. It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit thereof. 

What is claimed is:
 1. An aircraft engine run-up hangar comprising: a building defining a test chamber capable of receiving an aircraft therein; an air inlet structure; and an exhaust structure; wherein the air inlet structure is formed in a front end part of a roof structure corresponding to a front end part of the building, the exhaust structure is connected to a rear end part of the building and defines an exhaust passage extending obliquely upward from the back end of the building, a ceiling included in the building has an inclined section sloping down backward to straighten air currents, and a groove is formed in a middle part, with respect to width, of the inclined section to permit a vertical tail fin of an aircraft to pass when the aircraft is carried into or out of the test chamber.
 2. The aircraft engine run-up hangar according to claim 1, wherein the inclined section has laterally opposite parts respectively extending on the opposite sides of the groove 31 and sloping down toward right and left side wall structures.
 3. The aircraft engine run-up hangar according to claim 1, wherein a reverse flow stopping plate of a width approximately equal to that of the test chamber is suspended from the ceiling of the test chamber so as to extend in front of the vertical tail fin of the aircraft placed in the test chamber.
 4. The aircraft engine run-up hangar according to claim 3, wherein a vertical tail fin passing gap that permits the vertical tail fin to pass when carrying the aircraft into or out of the test chamber is formed in a middle part, with respect to width, of the reverse flow stopping plate, and the vertical tail fin passing gap can be closed or opened by a reverse flow stopping cover.
 5. The aircraft engine run-up hangar according to claim 3, wherein the reverse flow stopping plate is disposed near the back end of the inclined section of the ceiling.
 6. The aircraft engine run-up hangar according to claim 1, wherein an air inlet structure through which fresh air can be taken into the building is formed at a position on the roof structure corresponding to a position in front of the groove formed in the inclined section of the ceiling.
 7. The aircraft engine run-up hangar according to claim 1, wherein a pair of current-straightening plates for the run-up of the tail engine of the aircraft are extended down from the opposite side walls of the groove formed in the inclined section of the ceiling to straighten air currents flowing toward the tail engine of the aircraft.
 8. The aircraft engine run-up hangar according to claim 7, wherein the current-straightening plates for the run-up of the tail engine is formed from a metal net, a textile net, a perforated plate, a slit plate or an expanded metal.
 9. The aircraft engine run-up hangar according to claim 1, wherein the building has right and left side walls respectively having back half sections extended obliquely toward each other such that the distance between the back half sections decreases toward the back.
 10. The aircraft engine run-up hangar according to claim 9, wherein sound-absorbing structures are incorporated into the right and the left side wall.
 11. The aircraft engine run-up hangar according to claim 1, wherein the exhaust structure has a width substantially equal to that of a back end part of the building.
 12. The aircraft engine run-up hangar according to claim 11, wherein the exhaust structure is joined to the back end of the building so as to extend over the entire width of the back end of the building.
 13. The aircraft engine run-up hangar according to claim 12, wherein the exhaust structure has an upward curving or bending passage.
 14. The aircraft engine run-up hangar according to claim 11, wherein the exhaust structure has main engine exhaust ducts through which exhaust gas discharged from main engines supported on the right and the left main wing of the aircraft is exhausted, and a tail engine exhaust duct through which exhaust gas discharged from the tail engine of the aircraft is exhausted.
 15. The aircraft engine run-up hangar according to claim 14, wherein each of the main engine exhaust ducts has a vertical part vertically rising at the back end of the building.
 16. The aircraft engine run-up hangar according to claim 14, wherein the tail engine exhaust duct defines a passage curved or bent obliquely upward toward the back.
 17. The aircraft engine run-up hangar according to claim 1, wherein curved connecting members connect parts of the inclined section of the ceiling extending on the opposite sides of the groove formed in the inclined section, and the opposite side walls of the groove formed in the inclined section, respectively. 